Prerequisites for Top-N Reports

Restrictions for Top-N Reports

Information About Top-N Reports

Top-N Reports Overview

Top-N reports allows you to collect and analyze data for each physical port on a switch. When Top-N reports start, they obtain statistics from the appropriate hardware counters and then go into sleep mode for a user-specified interval. When the interval ends, the reports obtain the current statistics from the same hardware counters, compare the current statistics from the earlier statistics, and store the difference. The statistics for each port are sorted by one of the statistic types that are listed in Table 55-1.

Table 55-1 Valid Top-N Statistic Types

Statistic Type

Definition

broadcast

Number of input/output broadcast packets

bytes

Number of input/output bytes

errors

Number of input errors

multicast

Number of input/output multicast packets

overflow

Number of buffer overflows

packets

Number of input/output packets

utilization

Utilization

Note When calculating the port utilization, Top-N reports bundles the Tx and Rx lines into the same counter and also looks at the full-duplex bandwidth when calculating the percentage of utilization. For example, a Gigabit Ethernet port would be 2000-Mbps full duplex.

Top-N Reports Operation

When you enter the collect top command, processing begins and the system prompt reappears immediately. When processing completes, the reports are not displayed immediately on the screen; the reports are saved for later viewing. The Top-N reports notify you when the reports are complete by sending a syslog message to the screen.

To view the completed reports, enter the show top counters interface report command. Only completed reports are displayed. For reports that are not completed, there is a short description of the process information.

To terminate a Top-N reports process, enter the clear top counters interface report command. Pressing Ctrl-C does not terminate Top-N reports processes. The completed reports remain available for viewing until you remove them by entering the clear top counters interface report {all | report_num} command.

•You can specify the number of busiest ports for which to create reports (the default is 20).

•You can specify the statistic type by which ports are determined to be the busiest (the default is utilization). The supported values for statistic_type are broadcast, bytes, errors, multicast, overflow, packets, and utilization.

•You can specify the interval over which statistics are collected (range: 0 through 999; the default is 30 seconds).

•Except for a utilization report (configured with the sort-by utilization keywords), you can specify an interval of zero to create a report that displays the current counter values instead of a report that displays the difference between the start-of-interval counter values and the end-of-interval counter values.

This example shows how to enable Top-N reports creation for an interval of 76 seconds for the four ports with the highest utilization: